1. Technical Field
This disclosure relates to switching power supplies and, more particularly, measuring the efficiency of switching power supplies.
2. Description of Related Art
Determining the efficiency of a switching power-supply in situ is an area of growing interest. An incremental reduction in overall power consumption and/or power consumption cost for a plurality of DC-DC converters and their associated loads may be realized by continuously optimizing load allocations in response to changes in the efficiency of one or more of the individual DC-DC converters. In order to make these decisions, real-time information regarding power-conversion efficiency may be required.
Accurately measuring a low-loss, step-down DC-DC converter's efficiency in situ can be challenging. The large output currents and low output voltages required from some high-efficiency step-down DC-DC converters can make the use of a sense resistor to measure output current unattractive. Relying instead upon the internal resistance of the switching inductor can also be problematic. The value of this resistance may vary due to manufacturing tolerances and temperature changes during operation. Thus, it can be difficult to accurately measure efficiency because of difficulties in accurately measuring output current.